This icy world, temporarily named 2017 OF201, could be a distant cousin of Pluto — and scientists mean "distant" quite ...

Astronomers have discovered a mysterious dwarf planet, 2017 OF201, far beyond Pluto. This discovery challenges existing ...

Scientists have discovered a mysterious new object far beyond Neptune, and it could be one of the most distant dwarf planets ...

It's an evocative idea that has long bedeviled scientists: a huge and mysterious planet is lurking in the darkness at the ...

U.S. astronomers hunting for "Planet Nine" have instead stumbled on what appears to be a new dwarf planet in the solar system's outer reaches.

Some astronomers say the strange, clustered orbits of icy rocks beyond Neptune indicate that something big is out there, ...

There’s a new frozen oddball orbiting the Sun, and it’s not your average space rock. It’s a planet—a minor one, to be ...

a name proposed for a hypothetical world beyond Neptune more than a century ago. Back in 1930, astronomers were searching for Planet X when they discovered Pluto, which became our solar system’s ...

Cheng, together with graduate students from Princeton University, discovered the potential dwarf planet while searching for ...